Active energy beam-curable composition, ink containing the same, and printer accommodating the same ink

ABSTRACT

An active energy beam-curable composition comprises a photo-cationic polymerizable substance; a photo-cationic polymerization initiator; and a polymerizable compound having an ethylenic unsaturated double bond such as monomethacrylate, dimethacrylate, monoacrylate, and diacrylate. Owing to the compound having the ethylenic unsaturated double bond contained in the composition, it is possible to suppress the occurrence of odor and cloudiness even when the composition is heated after being cured.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an active energy beam-curablecomposition which is quickly cured by irradiation with an active energybeam such as ultraviolet radiation and electron beam, which causesneither odor nor cloudiness even when the cured composition is heated,and which has a low viscosity with good operation performance. Thepresent invention also relates to an ink which contains the energybeam-curable composition, and a printer which accommodates the ink.

[0003] 2. Description of the Related Art

[0004] The active energy beam curing technique is extremely important ina variety of industries including, for example, wood coating, metalpainting, and printing, because of various characteristics including,for example, the quick curing speed, the good operation performancegenerally brought about by the absence of solvent, and the extremely lowamount of required energy. Especially, the photo-cationic polymerizationis attractive, because of the sufficient possibility to realize avariety of chemical and physical characteristics by means ofpolymerization of various monomers. In the photo-cationicpolymerization, the polymerization is not inhibited by oxygen.Therefore, it is unnecessary to carry out the polymerization in an inertatmosphere. The photo-cationic polymerization is advantageous in thatthe polymerization can be performed quickly and completely in the air.

[0005] However, the conventional active energy beam-curable compositioninvolves the following problem. That is, when the active energybeam-curable composition is further heated after being subjected tocoating and curing on a base material such as wood, metal, and paper,any odor is caused by the volatile component thereof, for example, anyuncured remaining monomer.

[0006] When the active energy beam-curable composition is used at theinside of an instrument or the like, the following problem also arises.That is, when the active energy beam-curable composition itselfundergoes a high temperature, any cloudiness appears in the instrumentdue to the volatile component of the active energy beam-curablecomposition.

[0007] Taking the handling of the active energy beam-curable compositioninto consideration, it is desirable that the active energy beam-curablecomposition itself has a low viscosity before being cured. Therefore,when the active energy beam-curable composition contains aphoto-cationic polymerizable substance and a polymerization initiator, alow viscosity polymerizable substance such as vinyl ether is used as adiluent in order to lower the viscosity. However, when the low viscositypolymerizable substance such as vinyl ether is used, the followingproblem arises. That is, when the cured composition is heated asdescribed above, then the volatilization occurs, and the odor and thecloudiness are caused.

SUMMARY OF THE INVENTION

[0008] The present invention has been made in order to solve theproblems as described above, an object of which is to provide an activeenergy beam-curable composition which has a low viscosity with goodoperation performance, which avoids the appearance of the volatilecomponent even when the active energy beam-curable composition is curedand heated thereafter, and which makes it possible to avoid theoccurrence of the odor and the cloudiness, an ink containing thecomposition, and an ink discharging apparatus with an ink containerwhich accommodates the ink.

[0009] According to a first aspect of the present invention, there isprovided an active energy beam-curable composition comprising:

[0010] a photo-cationic polymerizable substance;

[0011] a photo-cationic polymerization initiator; and

[0012] a polymerizable compound having an ethylenic unsaturated doublebond.

[0013] In the present invention, the active energy beam-curablecomposition, which comprises the photo-cationic polymerizable substanceand the photo-cationic polymerization initiator, contains thepolymerizable compound having the ethylenic unsaturated double bond. Thepolymerizable compound having the ethylenic unsaturated double bond maybe, for example, monomethacrylate, dimethacrylate, monoacrylate, ordiacrylate. It is considered that the polymerizable compound having theethylenic unsaturated double bond as described above is polymerized bythe irradiation with the active energy beam (radical polymerization),and the polymerizable compound having the ethylenic unsaturated doublebond forms a bonding state by means of any chemical reaction togetherwith the photo-cationic polymerizable substance. Therefore, even whenthe composition, which has been cured by the irradiation with the activeenergy beam, is heated again, then the volatile component, which is anyremaining monomer, exists in an extremely small amount, and thus theodor and the cloudiness are scarcely caused. Further, the compound asdescribed above has a relatively low viscosity. Therefore, it is easy tohandle the active energy beam-curable composition.

[0014] In view of the prevention of the cloudiness and the odor whichwould be otherwise caused by the cured composition, the photo-cationicpolymerizable substance preferably contains an epoxy resin compound.Especially, an alicyclic epoxy resin compound is preferred, because itenhances the crosslinking degree of the active energy beam-curablecomposition. Alternatively, the photo-cationic polymerizable substancemay be an oxetane compound. When the oxetane compound is used, it ispossible to more effectively avoid the cloudiness and the odor when thecured composition is heated.

[0015] The photo-cationic polymerization initiator may contain an oniumsalt. When the onium salt is used, then the crosslinking degree of theactive energy beam-curable composition is enhanced, and it is possibleto more effectively avoid the cloudiness and the odor when the curedcomposition is heated.

[0016] The active energy beam-curable composition may be a color orcolorless (transparent) ink, for example, an ink to be preferably usedfor the ink-jet (or ink discharging) application. In this case, thecomposition may contain, for example, a coloring agent of a syntheticdye or a pigment, an inorganic filler, a surface-treating agent (asurfactant and/or a dispersing agent), a viscosity-adjusting agent, atreating agent, and an ultraviolet radiation-blocking agent, in additionto the photo-cationic polymerizable substance and the polymerizationinitiator. When the composition is used as the ink for the ink-jetapplication, the composition is prepared so that the viscosity of thecomposition upon discharging the ink from an ink jet head (inkdischarging head) is 2 cps to 30 cps.

[0017] The content of the polymerizable compound having the ethylenicunsaturated double bond is preferably about 5% by weight to about 58% byweight, in view of the fact that the occurrence of the odor and thecloudiness is avoided. Further, when the composition is used for an inkhead of an ink jet apparatus (or ink discharging apparatus) whichperforms photo-molding or photo-curing printing, the content of thepolymerizable compound having the ethylenic unsaturated double bond ispreferably about 10% by weight to about 48% by weight. The content ofthe polymerizable compound having the ethylenic unsaturated double bondaffects the viscosity of the composition. Therefore, when thecomposition is used as the ink for the ink-jet application, the contentis preferably adjusted within a range in which the viscosity of thecomposition upon discharging the ink from an ink jet head is 2 cps to 30cps.

[0018] According to a second aspect of the present invention, there isprovided an ink discharging apparatus comprising:

[0019] an ink discharging head which discharges an ink;

[0020] an ink tank which stores the ink to be supplied to the inkdischarging head; and

[0021] a light source which is used to cure the discharged ink, whereinthe ink comprises:

[0022] a photo-cationic polymerizable substance;

[0023] a photo-cationic polymerization initiator; and

[0024] a polymerizable compound having an ethylenic unsaturated doublebond.

[0025] In the ink discharging apparatus of the present invention, theink, which has been discharged by the ink discharging head, for example,onto the impermeable surface of those of wood, metal or the like, iscured with the light source such as the ultraviolet radiation. The inkcontains the photo-cationic polymerizable substance, the photo-cationicpolymerization initiator, and the polymerizable compound having theethylenic unsaturated double bond. Therefore, the ink has a preferredviscosity to be discharged from the ink discharging head. Even when thecured ink is heated, neither odor nor cloudiness is caused. The inkdischarging apparatus may be provided, for example, as a dispenser, acoater, and a printer. The ink tank may be an ink container fixedlyprovided in the apparatus or an ink cartridge which is replaceable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] An embodiment of the invention will be described in detail withreference to the following figures wherein:

[0027]FIG. 1A is a plan view of a color ink jet printer of a firstembodiment of the invention;

[0028]FIG. 1B is a front view of the color ink jet printer of the firstembodiment;

[0029]FIG. 2 is a schematic block diagram showing a control system ofthe ink jet printer of the first embodiment; and

[0030]FIG. 3 is a flowchart of control processing to be executed in theink jet printer of an embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The present invention will be explained in detail below. Atfirst, explanation will be made for the substances to be used for thepresent invention.

(A) Photo-Cationic Polymerizable Substance

[0032] The photo-cationic polymerizable substance (A) (hereinafterreferred to as “component (A)” as well) is an organic compound whichcauses the polymerization reaction and/or the crosslinking reaction bybeing irradiated with light in the presence of the cationicphotopolymerization initiator. The photo-cationic polymerizablesubstance (A) includes, for example, epoxy compound, oxetane compound,oxolane compound, cyclic acetal compound, cyclic lactone compound,thiirane compound, thietane compound, Spiro ortho ester compound asreaction product of epoxy compound and lactone, cyclic ether compound,and cyclic thioether compound.

[0033] The photo-cationic polymerizable substance based on the oxetanecompound is a compound having one or more oxetane ring or oxetane ringsrepresented by the following formula (1).

[0034] The compound causes the polymerization reaction and/or thecrosslinking reaction by being irradiated with light in the presence ofthe cationic polymerizable photopolymerization initiator.

[0035] Various compounds may be used as the compound having the oxetanering as described above, provided that the compound has one or moreoxetane ring or oxetane rings. The compound will be exemplified below.

[0036] The compound, which has one oxetane ring, includes, for example,compounds represented by the following general formula (2).

[0037] In the general formula (2), Z represents oxygen atom or sulfuratom. R¹ represents hydrogen atom; fluorine atom; alkyl group having anumber of carbon atom or carbon atoms of 1 to 6 such as methyl group,ethyl group, propyl group, and butyl group; fluoroalkyl group having anumber of carbon atom or carbon atoms of 1 to 6 such as trifluoromethylgroup, perfluoroethyl group, and perfluoropropyl group; aryl grouphaving a number of carbon atoms of 6 to 18 such as phenyl group andnaphthyl group; furyl group; and thienyl group. R² represents, forexample, hydrogen atom; alkyl group having a number of carbon atom orcarbon atoms of 1 to 6 such as methyl group, ethyl group, propyl group,and butyl group; alkenyl group having a number of carbon atoms of 2 to 6such as 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group,2-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group, and3-butenyl group; aryl group having a number of carbon atoms of 6 to 18such as phenyl group, naphthyl group, anthranyl group, and phenanthrylgroup; substituted or unsubstituted aralkyl group having a number ofcarbon atoms of 7 to 18 such as benzyl group, fluorobenzyl group,methoxybenzyl group, fenetyl group, styryl group, cinnamyl group, andethoxybenzyl group; group having another aromatic ring such asaryloxyalkyl including, for example, phenoxymethyl group andphenoxyethyl group; alkylcarbonyl group having a number of carbon atomsof 2 to 6 such as ethylcarbonyl group, propylcarbonyl group, andbutylcarbonyl group; alkoxycarbonyl group having a number of carbonatoms of 2 to 6 such as ethoxycarbonyl group, propoxycarbonyl group, andbutoxycarbonyl group; and N-alkylcarbamoyl group having a number ofcarbon atoms of 2 to 6 such as ethylcarbamoyl group, propylcarbamoylgroup, butylcarbamoyl group, and pentylcarbamoyl group.

[0038] The compound, which has two oxetane rings, includes, for example,compounds represented by the following general formula (3).

[0039] In the general formula (3), R¹ represents those as defined in thegeneral formula (2) described above. R³ represents, for example, linearor branched alkylene group usually having a number of carbon atom orcarbon atoms of 1 to 20 such as ethylene group, propylene group, andbutylene group; linear or branched poly(alkyleneoxy) group usuallyhaving a number of carbon atom or carbon atoms of 1 to 120 such aspoly(ethyleneoxy) group and poly(propyleneoxy) group; linear or branchedunsaturated hydrocarbon group such as propenylene group,methylpropenylene group, and butenylene group; carbonyl group; alkylenegroup containing carbonyl group; alkylene group containing carboxylgroup at intermediate position of molecular chain; and alkylene groupcontaining carbamoyl group at intermediate position of molecular chain.Alternatively, R³ may be polyvalent group selected from groupsrepresented by the following general formulas (4), (5), and (6).

[0040] In the general formula (4), R⁴ represents hydrogen atom; alkylgroup having a number of carbon atom or carbon atoms of 1 to 4 such asmethyl group, ethyl group, propyl group, and butyl group; alkoxy grouphaving a number of carbon atom or carbon atoms of 1 to 4 such as methoxygroup, ethoxy group, propoxy group, and butoxy group; halogen atom suchas chlorine atom and boron atom; nitro group; cyano group; mercaptogroup; lower alkylcarboxyl group; carboxyl group; or carbamoyl group. xrepresents an integer of 1 to 4.

[0041] In the general formula (5), R⁵ represents oxygen atom, sulfuratom, methylene group, —NH—, —SO—, —SO₂—, —C(CF₃)₂—, or —C(CH₃)₂—.

[0042] In the general formula (6), R⁶ represents alkyl group having anumber of carbon atom or carbon atoms of 1 to 4 such as methyl group,ethyl group, propyl group, and butyl group; or aryl group having anumber of carbon atoms of 6 to 18 such as phenyl group and naphthylgroup. y is an integer of 0 to 200. R⁷ represents alkyl group having anumber of carbon atom or carbon atoms of 1 to 4 such as methyl group,ethyl group, propyl group, and butyl group; or aryl group having anumber of carbon atoms of 6 to 18 such as phenyl group and naphthylgroup. R⁷ may be a group represented by the following general formula(7).

[0043] In the general formula (7), R⁸ represents alkyl group having anumber of carbon atom or carbon atoms of 1 to 4 such as methyl group,ethyl group, propyl group, and butyl group; or aryl group having anumber of carbon atoms of 6 to 18 such as phenyl group and naphthylgroup. z is an integer of 0 to 100.

[0044] Specifically, the compound, which has two oxetane rings,includes, for example, compounds represented by the following generalformulas (8), (9), and (10).

[0045] In the general formula (10), R¹ represents those as defined inthe general formula (2) described above.

[0046] The compound, which has three or more oxetane rings, includes,for example, compounds represented by the following general formula(11).

[0047] In the general formula (11), R¹ represents those as defined inthe general formula (2) described above. R⁹ represents trivalent todecavalent organic groups including, for example, branched or linearalkylene group having a number of carbon atom or carbon atoms of 1 to 30such as groups represented by the following formulas (12) to (14),branched poly(alkyleneoxy) group such as groups represented by thefollowing formula (15), and linear or branched polysiloxane-containinggroups represented by the following formula (16) or (17). j representsan integer of 3 to 10 equal to the valency number of R⁹.

[0048] In the formula (12), R¹⁰ represents alkyl group having a numberof carbon atom or carbon atoms of 1 to 6 such as methyl group, ethylgroup, and propyl group.

[0049] In the formula (15), L's are the same or different from eachother, each of which is an integer of 1 to 10.

[0050] Specifically, the compound, which has four or more oxetane rings,includes, for example, a compound represented by the following formula(18).

[0051] The compound represented by the following general formula (19)may have 1 to 10 oxetane ring or oxetane rings.

[0052] In the formula (19), R¹ represents those as defined in thegeneral formula (2). R⁸ represents those as defined in the generalformula (7). R¹¹ represents alkyl group having a number of carbon atomor carbon atoms of 1 to 4 such as methyl group, ethyl group, propylgroup, and butyl group; or trialkylsilyl group (in this case, alkylgroups are the same or different from each other, including those havinga number of carbon atoms of 3 to 12 such as trimethylsilyl group,triethylsilyl group, tripropylsilyl group, and tributylsilyl group), andr represents an integer of 1 to 10.

[0053] Other than the examples described above, the compound (A) havingthe oxetane ring further includes compounds having a high molecularweight, i.e., a number average molecular weight of about 1000 to 5000 asconverted into a value of polystyrene measured by the gel permeationchromatography. Such a compound includes compounds represented by thefollowing formulas (20), (21), and (22) by way of example.

[0054] In the formula (20), p represents an arbitrary integer. In theformula (21), q represents an arbitrary integer. In the formula (22), srepresents an integer of 20 to 200. Specified examples of the compound(A) having the oxetane ring or oxetane rings explained above are asfollows.

[0055] Compound Having One Exetane Ring

[0056] For example, there may be exemplified3-ethyl-3-hydroxymethyloxetane, 3-(meta)allyloxymethyl-3-ethyloxetane,(3-ethyl-3-oxetanylmethoxy)methylbenzene,4-fluoro-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,4-methoxy-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,[1-(3-ethyl-3-oxetanylmethoxy)ethyl]phenyl ether,isobutoxymethyl(3-ethyl-3-oxetanylmethyl)ether,isobornyloxyethyl(3-ethyl-3-oxetanylmethyl)ether,isobornyl(3-ethyl-3-oxetanylmethyl) ether,2-ethylhexyl(3-ethyl-3-oxetanylmethyl) ether, ethyldiethyleneglycol(3-ethyl-3-oxetanylmethyl) ether,dicyclopentadiene(3-ethyl-3-oxetanylmethyl) ether,dicyclopentenyloxyethyl(3-ethyl-3-oxetanylmethyl)ether,dicyclopentenyl(3-ethyl-3-oxetanylmethyl)ether,tetrahydrofurfuryl(3-ethyl-3-oxetanylmethyl)ether,tetrabromophenyl(3-ethyl-3-oxetanylmethyl)ether,2-tetrabromophenoxyethyl(3-ethyl-3-oxetanylmethyl)ether,tribromophenyl(3-ethyl-3-oxetanylmethyl)ether,2-tribromophenoxyethyl(3-ethyl-3-oxetanylmethyl)ether,2-hydroxyethyl(3-ethyl-3-oxetanylmethyl)ether,2-hydroxypropyl(3-ethyl-3-oxetanylmethyl)ether,butoxyethyl(3-ethyl-3-oxetanylmethyl)ether,pentachlorophenyl(3-ethyl-3-oxetanylmethyl)ether,pentabromophenyl(3-ethyl-3-oxetanylmethyl)ether, andbornyl(3-ethyl-3-oxetanylmethyl)ether.

[0057] Compound Having Two or More Oxetane Rings

[0058] For example, there may be exemplified3,7-bis(3-oxetanyl)-5-oxa-nonane,3,3′-(1,3-(2-methylenyl)propanediylbis(oxymethylene))bis-(3-ethyloxetane),1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene,1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane,1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether,dicyclopentenylbis(3-ethyl-3-oxetanylmethyl)ether, triethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether, tetraethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether,tricyclodecanediyldimethylene(3-ethyl-3-oxetanylmethyl)ether,trimethylolpropane tris(3-ethyl-3-oxetanylmethyl)ether,1,4-bis(3-ethyl-3-oxetanylmethoxy)butane,1,6-bis(3-ethyl-3-oxetanylmethoxy)hexane, pentaerythritoltris(3-ethyl-3-oxetanylmethyl)ether, pentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl)ether, polyethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritolhexakis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl)ether, caprolactone modifieddipentaerythritol hexakis(3-ethyl-3-oxetanylmethyl)ether, caprolactonemodified dipentaerythritol pentakis(3-ethyl-3-oxetanylmethyl)ether,ditrimethylolpropane tetrakis(3-ethyl-3-oxetanylmethyl)ether, EOmodified bisphenol A bis(3-ethyl-3-oxetanylmethyl)ether, PO modifiedbisphenol A bis(3-ethyl-3-oxetanylmethyl)ether, EO modified hydrogenatedbisphenol A bis(3-ethyl-3-oxetanylmethyl)ether, PO modified hydrogenatedbisphenol A bis(3-ethyl-3-oxetanylmethyl)ether, and EO modifiedbisphenol F (3-ethyl-3-oxetanylmethyl)ether. One species of the compoundas described above may be used singly. Alternatively, two or morespecies of the compounds as described above may be used in combination.

[0059] Among them, the compound having the oxetane ring, which may beused especially preferably as the component (A) of the resin compositionof the present invention, includes, for example,(3-ethyl-3-oxetanylmethoxy)methylbenzene represented by the followingformula (23), 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzenerepresented by the formula (24),1,2-bis(3-ethyl-3-oxetanylmethoxy)ethane represented by the formula(25), trimethylolpropane tris(3-ethyl-3-oxetanylmethyl)ether representedby the formula (26), and the compounds represented by the generalformula (19) described above.

[0060] One species of the compound having the oxetane ring as describedabove may be used singly. Alternatively, two or more species of thecompounds having the oxetane ring as described above may be used incombination.

[0061] Especially, it is desirable to use3-ethyl-3-hydroxymethyloxetane, di[1-ethyl(3-oxetanyl)]methyl ether, or3-ethyl-3-(2-ethylhexyloxymethyl)oxetane. When3-ethyl-3-hydroxymethyloxetane, di[1-ethyl(3-oxetanyl)]methyl ether, or3-ethyl-3-(2-ethylhexyloxymethyl)oxetane is used, then the reactionvelocity of the photo-cationic polymerization is quickened in thepresent invention, and it is possible to quickly obtain the activeenergy beam-curable composition of the present invention. The oxetanecompound is disclosed in detail in U.S. Pat. No. 5,463,084, the contentof which has been incorporated herein by reference.

[0062] The alicyclic epoxy resin compound may include, for example,3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate,2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane,bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene oxide,4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate,3,4-epoxy-6-methylcyclohexyl-3′,4′-epoxy-6′-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadienediepoxide, di(3,4-epoxycyclohexylmethyl)ether of ethylene glycol,ethylenebis(3,4-epoxycyclohexane carboxylate), epoxydized tetrabenzylalcohol, and lactone modified3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate.

[0063] The cationic polymerizable substance, which is especiallypreferred as the alicyclic epoxy resin compound, is the epoxy compoundhaving two or more alicyclic epoxy groups in one molecule, including,for example, 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate and bis(3,4-epoxycyclohexylmethyl)adipate.

[0064] Commercially available products of the cationic polymerizablesubstance, which are preferably usable as the alicyclic epoxy resincompound, may include, for example, UVR-6100, UVR-6105, UVR-6110, andUVR-6128 (all produced by Union Carbide Corporation), Celloxide 2021,Celloxide 2021P, and Celloxide 2021A (all produced by Daicel ChemicalIndustries, Ltd.), and KRM-2100 and KRM-2199 (both produced by AsahiDenka Co., Ltd.).

[0065] It has been confirmed that the use of the epoxy resin compoundmakes it possible to further avoid the appearance of the volatilecomponent and further avoid the occurrence of the odor and thecloudiness, even when the active energy beam-curable composition of thepresent invention is heated after being cured.

[0066] Especially, when the alicyclic epoxy resin compound is used, itis possible to enhance the crosslinking degree of the active energybeam-curable composition of the present invention. The occurrence of theodor and the cloudiness has been successfully avoided, when the activeenergy beam-curable composition of the present invention is heated afterbeing cured.

[0067] It is preferable that the photo-cationic polymerizable substanceother than the vinyl ether compound is used as the photo-cationicpolymerizable substance to be used for the present invention, for thefollowing reason. That is, if the vinyl ether compound is contained inthe composition, when the cured composition is heated, then acetaldehydeand crotonaldehyde are volatilized, and they cause the odor and thecloudiness. However, it is allowable that the photo-cationicpolymerizable substance other than the vinyl ether compound is used as amajor component of the photo-cationic polymerizable substance, and aminute amount of the vinyl ether compound is contained within a range inwhich no harmful influence is exerted on the odor and the cloudiness.

(B) Photo-Cationic Polymerization Initiator

[0068] The photo-cationic polymerization initiator (B) (hereinafterreferred to as “component (B)” as well), which constitutes the activeenergy beam-curable composition of the present invention, is thecompound capable of releasing the substance to initiate the cationicpolymerization by receiving the energy beam such as light. Especiallypreferred compounds may include the onium salt having the structurerepresented by the general formula (1). The onium salt is the compoundwhich releases Lewis acid when it receives light.

[R¹ _(a)R² _(b)R³ _(c)R⁴ _(d)Z]^(+m)[MX_(n+m)]^(−m)   General formula(1)

[0069] In the formula, the cation is onium. Z is S, Se, Te, P, As, Sb,Bi, O, I, Br, Cl, or N≡N. R¹, R², R³, and R⁴ are identical or differentorganic groups. a, b, c, and d are integers of 0 to 3 respectively.(a+b+c+d) is equal to the valency number of Z. M represents metalloid ormetal to constitute the central atom of the halide complex, including,for example, B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr,Mn, and Co. X represents halogen atom. m represents the net charge ofthe halide complex ion. n represents the number of atoms in the halidecomplex ion. Specifically, the anion (MX_(n+m)) in the general formula(1) described above includes, for example, tetrafluoroborate (BF₄ ⁻),hexafluorophosphate (PF₆ ⁻), hexafluoroantimonate (SbF₆ ⁻),hexafluoroarsenate (AsF₆ ⁻), and hexachloroantimonate (SbCl₆ ⁻).

[0070] Further, it is possible to use the onium salt having the anionrepresented by the general formula [MX_(n)(OH)⁻]. Furthermore, it isalso possible to use the onium salt having another anion such asperchlorate ion (ClO₄ ⁻), trifluoromethanesulfonate ion (CF₃SO₃ ⁻),fluorosulfonate ion (FSO₃ ⁻), toluenesulfonate ion,trinitrobenzenesulfonate anion, and trinitrotoluenesulfonate anion.

[0071] Among the onium salts as described above, the onium salt, whichis especially effective as the component (B), is the aromatic oniumsalt. Especially, it is preferable to use, for example, aromatichalonium salt described, for example, in Japanese Patent ApplicationLaid-open No. 50-151996 corresponding to England Patent No. 1516351 andJapanese Patent Application Laid-open No. 50-158680 corresponding toU.S. Pat. No. 4,394,403; VIA group aromatic onium salt described, forexample, in Japanese Patent Application Laid-open No. 50-151997corresponding to England Patent No. 1516511, Japanese Patent ApplicationLaid-open No. 52-30899 corresponding to U.S. Pat. No. 4,256,828,Japanese Patent Application Laid-open No. 56-55420 corresponding toEngland Patent No. 2061280, and Japanese Patent Application Laid-OpenNo. 55-125105 corresponding to U.S. Pat. No. 4,197,174; VA grouparomatic onium salt described, for example, in Japanese PatentApplication Laid-open No. 50-158698 corresponding to U.S. Pat. No.4,069,055; oxosulfoxonium salt described, for example, in JapanesePatent Application Laid-open No. 56-8428, Japanese Patent ApplicationLaid-open No. 56-149402, and Japanese Patent Application Laid-open No.57-192429 corresponding to U.S. Pat. No. 4,387,216; aromatic diazoniumsalt described, for example, in Japanese Patent Application Laid-openNo. 49-17040; and thiopyrylium salt described in U.S. Pat. No.4,139,655. It is also possible to refer, for example, to initiatorsbased on aluminum complex/photolysis silicon compound and iron/allenecomplex.

[0072] Commercially available products of the cationicphotopolymerization initiator, which are preferably usable as thecomponent (B), may include, for example, UVI-6950, UVI-6970, UVI-6974,and UVI-6990 (all produced by Union Carbide Corporation); ADEKA OptomerSP-150, SP-151, SP-170, and SP-171 (all produced by Asahi Denka Co.,Ltd.); Irgacure 261 (produced by Ciba-Geigy Corporation); CI-2481,CI-2624, CI-2639, and CI-2064 (all produced by NIPPON SODA CO., LTD.);CD-1010, CD-1011, and CD-1012 (all produced by Sartomer Company); andDTS-102, DTS-103, NAT-103, NDS-103, TPS-103, MDS-103, MPI-103, andBBI-103 (all produced by Midori Kagaku Co., Ltd.). Among thecommercially available products described above, UVI-6970, UVI-6974,ADEKA Optomer SP-170, SP-171, CD-1012, and MPI-103 are especiallypreferred, because it is possible to allow the resin compositioncontaining each of them to express the high curing sensitivity.

[0073] When the onium salt is contained, then it is possible to enhancethe crosslinking degree of the active energy beam-curable composition ofthe present invention, and the occurrence of the odor and the cloudinesshas been successfully avoided when the composition is heated after beingcured.

(C) Polymerizable Compound Having Ethylenic Unsaturated Double Bond

[0074] The polymerizable compound having the ethylenic unsaturateddouble bond (C) (hereinafter referred to as “component (C)” as well),which constitutes the active energy beam-curable composition of thepresent invention, may include, for example, monomethacrylate,dimethacrylate, monoacrylate, diacrylate monomer, multifunctionalmonomer, and oligoacrylate.

[0075] Components of monomethacrylate, dimethacrylate, monoacrylate, anddiacrylate monomers are summarized in Table 1 below. TABLE 1 TradeClassification Component (C) Name Maker monomethacrylatemethoxydiethylene M20G Shin-Nakamura glycol methacrylate Chemical Co.,(n = 2) Ltd. methoxydiethylene M40G Shin-Nakamura glycol methacrylateChemical Co., (n = 2) Ltd. laurylmethacrylate LMA Shin-Nakamura (n = 12)Chemical Co., Ltd. stearylmethacrylate S Shin-Nakamura (n = 18) ChemicalCo., Ltd. isostearyl- S-1800M Shin-Nakamura methacrylate Chemical Co.,Ltd. 2-hydroxy-3- G-201P Kyoeisha acryloyloxypropyl- Chemical Co.,methacrylate Ltd. dimethacrylate ethylene glycol 1G Shin-Nakamuradimethacrylate Chemical Co., (n = 1) Ltd. diethylene glycol 2GShin-Nakamura dimethacrylate Chemical Co., (n = 2) Ltd. triethyleneglycol 3G Shin-Nakamura dimethacrylate Chemical Co., (n = 3) Ltd.polyethylene glycol 4G Shin-Nakamura 200 dimethacrylate Chemical Co., (n= 4) Ltd. neopentyl glycol NPG Shin-Nakamura dimethacrylate ChemicalCo., Ltd. 1,3-butylene glycol BG Shin-Nakamura dimethacrylate ChemicalCo., Ltd. 1,4-butanediol BD Shin-Nakamura dimethacrylate Chemical Co.,Ltd. 3-methyl-1,5- MPD Shin-Nakamura pentanediol Chemical Co.,dimethacrylate Ltd. 1,6-hexanediol HD Shin-Nakamura methacrylateChemical Co., Ltd. 1,9-nonanediol NOD Shin-Nakamura methacrylateChemical Co., Ltd. 2-methyl-1,8- IND Shin-Nakamura octanediol ChemicalCo., dimethacrylate Ltd. (85%) + 1,9- nonanediol dimethacrylate (15%)1,10-decanediol DOD-N Shin-Nakamura dimethacrylate Chemical Co., Ltd.monoacrylate phenoxyethylene AMP-10G Shin-Nakamura glycol acrylateChemical Co., (n = 1) Ltd. phenoxyethylene AMP-20GY Shin-Nakamura glycolacrylate Chemical Co., (n = 2) Ltd. methoxyethylene AMP-30GShin-Nakamura glycol acrylate Chemical Co., (n = 3) Ltd. lauryl acrylateLA Shin-Nakamura Chemical Co., Ltd. isostearyl acrylate S-1800SShin-Nakamura Chemical Co., Ltd. morpholine acrylate ACMO Kohjin Co.,Ltd. lauryl acrylate Light- Kyoeisha Acrylate Chemical Co., L-A Ltd.stearyl acrylate Light- Kyoeisha Acrylate Chemical Co., S-A Ltd.butoxyethyl acrylate Light- Kyoeisha Acrylate Chemical Co., BO-A Ltd.monoacrylate methoxytriethylene Light- Kyoeisha glycol acrylate AcrylateChemical Co., MTG-A Ltd. isobornyl acrylate Light- Kyoeisha AcrylateChemical Co., IB-XA Ltd. phenoxypoly- Light- Kyoeisha ethylene acrylateAcrylate Chemical Co., P-200A Ltd. 2-ethylhexylcarbitol Aronix M-Toagosei Co., acrylate 120 Ltd. phenol EO modified Aronix M- ToagoseiCo., acrylate (n = 2) 101 Ltd. 4-hydroxybutyl 4-HBA Osaka Organicacrylate Chemical Industry Ltd. 3-methoxybutyl V#158 Osaka Organicacrylate Chemical Industry Ltd. benzyl acrylate V#160 Osaka OrganicChemical Industry Ltd. phenoxyethyl V#192 Osaka Organic acrylateChemical Industry Ltd. diacrylate dipropylene glycol APG-100Shin-Nakamura diacrylate Chemical Co., Ltd. tripropylene glycol APG-200Shin-Nakamura diacrylate Chemical Co., Ltd. neopentyl glycol A-NPG-SShin-Nakamura diacrylate Chemical Co., Ltd. 1,8-hexanediol A-HDShin-Nakamura acrylate Chemical Co., Ltd. 1,9-nonanediol A-NODShin-Nakamura acrylate Chemical Co., Ltd. 2-methyl-1,8- A-INDShin-Nakamura octanediol acrylate Chemical Co., (85%) + 1,9- Ltd.nonanediol acrylate (15%) triethylene glycol Light- Kyoeisha diacrylateAcrylate Chemical Co., 3EG-A Ltd. diacrylate PEG400# diacrylate Light-Kyoeisha Acrylate Chemical Co., 9EG-A Ltd. 1,9-nonanediol Light-Kyoeisha diacrylate Acrylate Chemical Co., 1,9ND-A Ltd. tripropyleneglycol Aronix M- Toagosei Co., diacrylate 220 Ltd. (TPGDA) polyethyleneglycol Aronix M- Toagosei Co., diacrylate 240 Ltd. (TEGDA)1,9-nonanediol V#260 Osaka Organic diacrylate Chemical Industry Ltd.tripropylene glycol V#310HP Osaka Organic diacrylate Chemical IndustryLtd. tripropylene glycol V#310HG Osaka Organic diacrylate ChemicalIndustry Ltd.

[0076] The multifunctional monomer may include, for example,trimethylolpropane triacrylate, pentaerythritol triacrylate,trimethylolpropane EO-added triacrylate, glycerol PO-added triacrylate,trisacryloyloxyethyl phosphate, and pentaerythritol tetraacrylate.

[0077] Further, the oligoacrylate may include, for example, tetrafurfuryl alcohol oligoacrylate, ethylcarbitol oligoacrylate,1,4-butanediol oligoacrylate, neopentyl glycol oligoacrylate,1,6-hexanediol oligoacrylate, trimethylolpropane oligoacrylate, andpentaerythritol oligoacrylate.

[0078] Commercially available products (other than those shown inTable 1) of the polymerizable compound having the ethylenic unsaturateddouble bond, which are preferably usable as the component (C), mayinclude, for example, V#295, V#300, V#360, V#GPT, V3PA, V#400, V#150D,V#190d, V#195D, V#215D, V#230D, V#295D, and V#400D (all produced byOsaka Organic Chemical Industry Ltd.), and TMPT, TMM-360, A-TMPT,A-TMPT-3EO, AT-30E, A-TMPT-3PO, A-9300, A-TMM-3, A-TMM-3L, A-TMM-T,ATM-2.4E, ATM-4E, ATM-35E, ATM-4P, AD-TMP, AD-TMP-L, and A-9530 (allproduced by Shin-Nakamura Chemical Co., Ltd.). The content of thepolymerizable compound having the ethylenic unsaturated double bond ispreferably about 5% by weight to about 58% by weight, in view of thefact that the occurrence of the odor and the cloudiness is avoided.Further, when the composition is used for an ink head of an ink jetapparatus (or ink discharging apparatus) which performs photo-molding orphoto-curing printing, the content of the polymerizable compound havingthe ethylenic unsaturated double bond is preferably about 10% by weightto about 48% by weight. The content of the polymerizable compound havingthe ethylenic unsaturated double bond affects the viscosity of thecomposition. Therefore, when the composition is used as the ink for theink-jet application, the content is preferably adjusted within a rangein which the viscosity of the composition upon discharging the ink froman ink jet head is 2 cps to 30 cps.

(D) Other Components

[0079] In addition to the essential components described above, theactive energy beam-curable composition of the present invention may beoptionally blended with inactive components such as an inorganic filler,a dye, a pigment, a viscosity-adjusting agent, a treating agent, and anultraviolet radiation-blocking agent. Further, if necessary, it ispossible to blend a component capable of radical polymerization with theactive energy beam, such as a radical photopolymerization initiator anda compound having (meth)acryloyl group.

[0080] When the active energy beam-curable composition of the presentinvention is cured with ultraviolet radiation, a photosensitizing agentmay be blended in order to further improve the curing performance.Typical sensitizing agents, which are usable in the present invention,include compounds disclosed by “Crivello” in Adv. in Polymer Sci., 62, 1(1984). Specifically, the sensitizing agent includes, for example,pyrene, perylene, acridine orange, thioxanthone, 2-chlorothioxanthone,and benzoflavin. When the active energy beam-curable composition of thepresent invention is used as an ink for ink-jet printing, the activeenergy beam-curable composition may contain, for example, a coloringagent such as a synthetic dye or a pigment, an inorganic filler, asurface-treating agent (a surfactant and/or a dispersing agent), aviscosity-adjusting agent, a treating agent, and an ultravioletradiation-blocking agent, in addition to the photo-cationicpolymerizable substance, the photo-cationic polymerization initiator,and the polymerizable compound having the unsaturated double bond. Whenthe composition is used as an ink for ink jet application, thecomposition is prepared so that the viscosity of the composition uponink jetting from an ink jet head is 2 cps to 30 cps. U.S. Pat. No.5,059,266 discloses, for example, additives, contents thereof, andcharacteristics of the ink when the active energy beam-curablecomposition is used as an ink for ink-jet printing. The content of thisUnited States Patent has been incorporated herein by reference. Theactive energy beam, which is used to cure the composition of the presentinvention, includes, ultraviolet radiation, infrared radiation, andelectron beam (EB).

[0081] Next, explanation will be made for inks (active energybeam-curable compositions) obtained in Examples and ComparativeExamples.

COMPARATIVE EXAMPLE 1

[0082] A transparent liquid composition was obtained by mixing andagitating, at room temperature in a dark room, a photo-cationicpolymerizable substance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof triethylene glycol divinyl ether (trade name: DVE-3, produced byISP), and a photo-cationic polymerization initiator, i.e., 4 parts byweight of a mixture of triarylsulfonium hexafluorophosphate salts andpropylene carbonate (trade name: UVI-6990, produced by Union CarbideCorporation, active ingredient: 50%).

COMPARATIVE EXAMPLE 2

[0083] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 20 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 80 parts byweight of ethylene glycol dimethacrylate (trade name: 1G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

COMPARATIVE EXAMPLE 3

[0084] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 70 parts byweight of ethylene glycol dimethacrylate (trade name: 1G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

COMPARATIVE EXAMPLE 4

[0085] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 20 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 80 parts byweight of 1,3-butylene glycol dimethacrylate (trade name: BG, producedby Shin-Nakamura Chemical Co., Ltd.), and a photo-cationicpolymerization initiator, i.e., 4 parts by weight of a mixture oftriarylsulfonium hexafluorophosphate salts and propylene carbonate(trade name: UVI-6990, produced by Union Carbide Corporation, activeingredient: 50%) were used.

COMPARATIVE EXAMPLE 5

[0086] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 70 parts byweight of 1,3-butylene glycol dimethacrylate (trade name: BG, producedby Shin-Nakamura Chemical Co., Ltd.), and a photo-cationicpolymerization initiator, i.e., 4 parts by weight of a mixture oftriarylsulfonium hexafluorophosphate salts and propylene carbonate(trade name: UVI-6990, produced by Union Carbide Corporation, activeingredient: 50%) were used.

EXAMPLE 1

[0087] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof isobornyl acrylate (trade name: IBXA, produced by Kyoeisha ChemicalCo., Ltd.), and a photo-cationic polymerization initiator, i.e., 4 partsby weight of a mixture of triarylsulfonium hexafluorophosphate salts andpropylene carbonate (trade name: UVI-6990, produced by Union CarbideCorporation, active ingredient: 50%) were used.

EXAMPLE 2

[0088] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof methoxydiethylene glycol methacrylate (trade name: M20G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 3

[0089] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof ethylene glycol dimethacrylate (trade name: 1G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 4

[0090] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof polyethylene glycol 200 dimethacrylate (trade name: 4G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 5

[0091] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof neopentyl glycol dimethacrylate (trade name: NPG, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 6

[0092] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof 1,3-butylene glycol dimethacrylate (trade name: BG, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 7

[0093] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof 1,6-hexanediol dimethacrylate (trade name: HD, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 8

[0094] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 30 parts byweight of limonene dioxide (produced by elf atochem), 40 parts by weightof tripropylene glycol diacrylate (trade name: APG-200, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE9

[0095] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 10 parts byweight of limonene dioxide (produced by elf atochem), 60 parts by weightof ethylene glycol dimethacrylate (trade name: 1G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 10

[0096] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 20 parts byweight of limonene dioxide (produced by elf atochem), 50 parts by weightof ethylene glycol dimethacrylate (trade name: 1G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 11

[0097] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 20 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 75 parts byweight of limonene dioxide (produced by elf atochem), 5 parts by weightof ethylene glycol dimethacrylate (trade name: 1G, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 12

[0098] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 10 parts byweight of limonene dioxide (produced by elf atochem), 60 parts by weightof 1,3-butylene glycol dimethacrylate (trade name: BG, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 13

[0099] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 20 parts byweight of limonene dioxide (produced by elf atochem), 50 parts by weightof 1,3-butylene glycol dimethacrylate (trade name: BG, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

EXAMPLE 14

[0100] A transparent liquid composition was obtained in the same manneras in Comparative Example 1 except that a photo-cationic polymerizablesubstance, i.e., 20 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (tradename: UVR-6110, produced by Union Carbide Corporation), 75 parts byweight of limonene dioxide (produced by elf atochem), 5 parts by weightof 1,3-butylene glycol dimethacrylate (trade name: BG, produced byShin-Nakamura Chemical Co., Ltd.), and a photo-cationic polymerizationinitiator, i.e., 4 parts by weight of a mixture of triarylsulfoniumhexafluorophosphate salts and propylene carbonate (trade name: UVI-6990,produced by Union Carbide Corporation, active ingredient: 50%) wereused.

I. Curing Method

[0101] The obtained composition was applied to a polyester film so thatthe thickness was about 15 μm, and then the composition was cured byallowing the composition to pass through twice an ultravioletradiation-irradiating apparatus of the conveyer type, the apparatusbeing installed with a super high voltage mercury lamp of 80 W/cm (lampheight: 155 mm, conveyer speed: 7.5 m/min., radiation intensity: 80mW/cm², 160 mJ/cm²). Test machine was Eye Mini Grandage ECS-151U (lampoutput: 1.0 kW, belt conveyer type, produced by Eye Graphics Co., Ltd.).

II. Cloudiness Test

[0102] A test piece (cured composition) was placed on a hot plate heatedto 110° C., and the test piece was covered with a glass vessel arrangedthereon. The cloudiness in the glass vessel, which possibly appearedafter being left to stand for 24 hours, was visually confirmed. The casewith no cloudiness is indicated by “+”, and the case with any cloudinesswas indicated by “−”.

[0103] The transparent liquid compositions (active energy beam-curablecompositions) obtained in Examples 1 to 14 and Comparative Examples 1 to5 described above were cured to perform the cloudiness test. Obtainedresults are summarized in Table 2 below. The polymerizable compoundseach having the unsaturated double bond (components (C)) used for therespective compositions are entered in Table 2. TABLE 2 Cloudiness testComponent (C) (110° C. × 24 H) Comparative Example 1 DVE-3Tech −Comparative Example 2 1G − Comparative Example 3 1G − ComparativeExample 4 BG − Comparative Example 5 BG − Example 1 IBXA + Example 2M20G + Example 3 1G + Example 4 4G + Example 5 NPG + Example 6 BG +Example 7 HD + Example 8 APG-200 + Example 9 1G + Example 10 1G +Example 11 1G + Example 12 BG + Example 13 BG + Example 14 BG +

[0104] According to Table 2, it has been confirmed that no cloudinessappears in the cloudiness test by containing monomethacrylate,dimethacrylate, monoacrylate, or diacrylate.

[0105] The liquid compositions obtained in Examples 1 to 14 were used astransparent inks to perform the printing by using a printer which willbe explained later. As a result, good output results were successfullyobtained, in which neither odor nor cloudiness appeared. On the otherhand, the liquid compositions obtained in Comparative Examples 1 to 5were used as inks to perform the printing by using a printer. As aresult, both of odor and cloudiness were confirmed.

[0106] An embodiment of an ink jet printer as an ink dischargingapparatus in accordance with the invention will be described as belowwith reference to the accompanying drawings.

[0107] Embodiments of the invention will be described with reference tothe accompanying drawings. As shown in FIG. 1, a color ink jet printer100 of a first embodiment includes a carriage 102 that can move in amain scanning direction (an X-axis direction) while guided by X-axisguide bars 101, 101 fixed to a frame F. A print head 104 as an inkdischarging head and ultraviolet (UV) lamps 105L, 105R are provided onthe carriage 102. The print head 104 includes a Y head 104Y for yellow(Y) ink, an M head 104M for magenta (M) ink, a C head 104C for cyan (C)ink and a K head 104K for black (K) ink. The ink to be ejected from theheads 104Y, 104M, 104C, 104K is an ultraviolet curing type ink (UV ink).The ink can be prepared by adding an coloring agent to the transparentliquid compositions prepared in the above examples. The heads 104Y,104M, 104C and 104K are aligned in a sub scanning direction (a Y-axisdirection), which is perpendicular to the main scanning direction, onthe carriage 102. The UV lamps 105L, 105R are provided on right and leftsides of the print head 104 so as to sandwich the print head 104therebetween.

[0108] The UV lamps 105L, 105R irradiate the UV ink, ejected from therespective ink heads onto a recording medium 103, with ultraviolet lightto increase its viscosity to cure the ink.

[0109] Each of the heads 104Y, 104M, 104C, 104K is formed with aplurality of nozzles, which face a platen 108 (described later) and arebasically aligned in parallel to the sub scanning direction. The Y head104Y, the M head 104M, the C head 104C and the K head 104K are connectedwith an yellow ink tank 104Y1 containing UV yellow ink, a magenta inktank 104M1 containing UV magenta ink, a cyan ink tank 104C1 containingUV cyan ink, a black ink tank 104K1 containing UV black ink,respectively. Each UV ink is supplied from the respective ink tanks104Y1, 104M1, 104C1, 104K1 to the respective nozzles through each inkflow path in the respective heads 104Y, 104M, 104C, 104K. Therefore,when one-line printing is performed by ejecting ink droplets of the UVink from each head 104Y, 104M, 104C, 104K while the carriage 102 ismoved in the main scanning direction, a printed portion is formed on therecording medium 103. A width of the printed portion is equal to acarriage traveling distance in the main scanning direction. A length ofthe printed portion is equal to a width of ink ejection from each head(a width of ink ejection from the nozzles in each head at a time).

[0110] An X-axis motor 106 that moves the carriage 102 in the subscanning direction is attached to one of side walls the frame F. Adriven pulley R is rotatably provided to the other side wall of theframe F. A timing belt 107 is stretched between the driven pulley R anda drive pulley P fixed to an output shaft of the X-axis motor 106. Thetiming belt 107 is engaged with the carriage 102. Thus, as the X-axismotor 106 is driven, the carriage 102 travels from side to side alongthe X-axis guide bars 101, 101, that is, the X-axis guide bars 101, 101and the X-axis motor 106 moves the carriage 102 in the main scanningdirection with respect to the recording medium 103. The platen 108 issupported by the frame F, under the carriage 102 and the X-axis guidebars 101, 101 so as to be movable in the sub scanning directionperpendicular to the main scanning direction. The platen 108 is formedwith a plurality of air-intakes at its top, and a recording medium 103,such as a plastic plate, is placed on the top. Air is taken in from theair-intakes with the recording medium 103 placed on the top (a surfacefor placing the recording medium 103), so that a negative pressure isgenerated and thus the recording medium 103 is statically held on theplaten 108. As described above, the platen 108 is provided with an airtaking mechanism for holding the recording medium 103. The air takingmechanism also functions as a holding device for holding the recordingmedium 103. The holding device is not limited to the air takingmechanism. However, various types of holding devices can be adopted. Forexample, a clamp mechanism that mechanically presses and holds therecording medium 103 on the platen 108 can be adopted.

[0111] A screw shaft 110, extending in a direction perpendicular to themain scanning direction, is rotatably supported by the frame F. One endof the screw shaft 110 is secured to an output shaft of a Y-axis motor109. A bearing 111, into which the screw shaft 110 is threaded, is fixedunder the platen 108. As the screw shaft 110 is rotated by the Y-axismotor 109, the platen 108 is moved in the sub scanning direction. Ascrew mechanism having the screw shaft 110, the bearing 111 and theY-axis motor 109 moves the platen 108 in the sub scanning direction withrespect to the carriage 102.

[0112] The amount and direction of travel of the carriage 102 iscontrolled by controlling the amount and direction of rotation of theX-axis motor 106. For example, a pulse motor is preferably used as theX-axis motor 106. The amount and direction of travel of the platen 108is controlled by controlling the amount and direction of rotation of theY-axis motor 109. For example, a pulse motor is preferably used as theY-axis motor 109.

[0113] An area 112 is a maintenance area in which purging, wiping,flushing and the like are performed. As shown in FIG. 1A, the UV lamps105L, 105R are longer than the print head 104 in a direction of feedingthe recording medium 103 by a predetermined length.

[0114] As shown in FIG. 2, a control system of the color ink jet printer100 includes a CPU 201, a ROM 202, an EEPROM 202 a, a RAM 203, an inputinterface 204 and an output interface 205. The output interface 205 isconnected with a Y head drive circuit 206Y, an M head drive circuit206M, a C head drive circuit 206C, a K head drive circuit 206K, anX-axis motor drive circuit 207, a Y-axis motor drive circuit 208 and UVlamp drive circuits 209L, 209R. A control signal and data from apersonal computer 220 are inputted to the input interface 204.

[0115]FIG. 3 is a flowchart for performing print control processing. Atfirst, the CPU 201 determines whether a command to start printing hasbeen issued from the personal computer 220 (S301). When the CPU 201determines that the command to start printing has been issued(S301:YES), the CPU 201 receives print data (S302). After the CPU 201receives a page of print data, the CPU 201 stores the print data in theRAM 203 and develops the print data into one page of data of each colorof Y, M, C, K (S303). Then, the CPU 201 lights the UV lamps 105L, 105R(S304). After that, based on the Y data, while outputting one line ofdot data to the Y head drive circuit 206Y, the CPU 201 performs one-lineprinting in the UV yellow ink by moving the carriage 102 in the mainscanning direction (S305).

[0116] One-line printing is performed as described below. A print datadeveloping area for one page is provided according to color in the RAM203. One page of dot data is developed into each print data developingarea in the bitmap format in which dots are aligned in the main scanningdirection and in the sub scanning direction. Each dot in the dot datarepresents ejection (nonejection) of an ink droplet from one nozzle.One-line printing of dot data is that dots equal to the number ofnozzles aligned in the sub scanning direction are selected in the subscanning direction and rows of the selected dots are aligned in the mainscanning direction from a print start side to a print end side. Dotsequal to the number of nozzles aligned in the sub scanning direction areselected and referred to as dot rows. While the dot rows aresequentially read from the print data developing area from the printstart side to the print end side and supplied to each heads 104Y, 104M,104C, 104K, the print head 104 is moved in the main scanning direction,thereby one line of a printed portion is formed on a recording medium103. Upon performing the printing, a printed portion is irradiated withultraviolet light by the UV lamps 105L, 105R disposed adjacent to theprint head 104 to increase its viscosity.

[0117] Next, the CPU 201 moves the platen 108 in the sub scanningdirection by one line (by the width of the ink ejection from the printhead 104). Then, while outputting each one line of the dot data to therespective Y and M head drive circuits 206Y and 206M based on each Y andM data, respectively, the CPU 201 performs one-line printing in each ofthe UV yellow ink and the UV magenta ink by moving the carriage 102 inthe main scanning direction (S306).

[0118] That is, at S305, one-line printing of the first line of the Ydata has been performed. Therefore, next, dot data of the Y data for asecond line is selected and provided to the Y head drive circuit 206Yand dot data of the M data for a first line is selected and provided tothe M head drive circuit 206M. In other words, ink droplets of the UVmagenta ink to be ejected according to the M data are ejected on thefirst line of the UV yellow ink ejected at S305. However, the viscosityof the UV yellow ink ejected prior to the ejection of the UV magenta inkhas already been increased by the irradiation by the UV lamps 105L,105R, so that the UV yellow ink and the UV magenta ink do not intermixand clarity of the ink colors is not degraded. Upon performing theprinting in each of the UV yellow ink and the UV magenta ink, the UVyellow ink and the UV magenta ink ejected at S306 are irradiated withultraviolet light by the UV lamps 105L, 105R to increase theirviscosity.

[0119] Next, the CPU 201 moves the platen 108 in the sub scanningdirection by one line. Then, while outputting each one line of the dotdata to the respective Y, M and C head drive circuits 206Y, 206M and206C based on each Y, M and C data, respectively, the CPU 201 performsone-line printing in each of the UV yellow ink, the UV magenta ink andthe UV cyan ink by moving the carriage 102 in the main scanningdirection (S307).

[0120] That is, dot data of the Y data for a third line, dot data of theM data for a second line and dot data of the C data for a first line areselected and supplied to the Y head drive circuit 206Y, the M head drivecircuit 206M and the C head drive circuit 206C, respectively. In otherwords, ink droplets of the UV cyan ink to be ejected according to the Cdata are ejected on the first line of the UV magenta ink ejected atS306. However, the viscosity of the UV magenta ink has already beenincreased by the irradiation by the UV lamps 105L, 105R, so that the UVmagenta ink and the UV cyan ink do not intermix and clarity of the inkcolors is not degraded. In short, the first line of the UV magenta inkis ejected over the first line of the UV yellow ink, and the first lineof the UV cyan ink is ejected over the first line of the UV magenta ink.One-line printing according to the M and Y data is also performed in thesame manner described above.

[0121] Next, the CPU 201 moves the platen 108 in the sub scanningdirection by one line. Then, while outputting each one line of the dotdata to the respective Y, M, C and K head drive circuits 206Y, 206M,206C and 206K based on each Y, M, C and K data, respectively, the CPU201 performs one-line printing in each of the UV yellow ink, the UVmagenta ink, the UV cyan ink and the UV black ink by moving the carriage102 in the main scanning direction. (S308).

[0122] That is, dot data of the Y data for a fourth line, dot data ofthe M data for a third line, dot data of the C data for a second lineand dot data of the K data for a first line are selected and supplied tothe Y head drive circuit 206Y, the M head drive circuit 206M, the C headdrive circuit 206C and the K head drive circuit 206K, respectively. AtS308, if the K data to be read is dot data for a Nth line (N is a wholenumber), the Y dot data is dot date for N+3th line, the M data is dotdata for N+2th line and the C data is dot data for N+1th line. If theCPU 201 makes a determination in the negative at S309 described later,the CPU 201 sequentially increments N and reads dot data. The ejectedink droplets are irradiated with the ultraviolet light to increase theirviscosity immediately after the ink droplets are ejected.

[0123] Then, the CPU 201 determines whether all printing has completed(S309). If the printing has not completed yet (S309:NO), dot data ofeach of the Y, M, C and K data for a next line is read and printing isperformed according to the data at S308 until the printing is completed.

[0124] The repetition of the one-line printing and the transport of theplaten 108 will make the printing operation reach a last line in orderof the Y head 104Y, the M head 104M, the C head 104C and the K head104K. When dot data that is to be used for printing is not left as toall the heads 104Y, 104M, 104C, 104K, the CPU 201 determines that theprinting has completed. At S308, dot data of each color is read. At thattime, if dot data of each color has already been used for printing in alast line, the CPU 201 outputs dot data that means nonejection of ink asto the dot data of each color.

[0125] When the CPU 201 determines that the printing has completed(S309:YES), the CPU 201 moves the carriage 102 at idle by three lineswithout ejecting ink droplets from the heads 104Y, 104M, 104C, 104K(S312). The UV black ink ejected last is irradiated with the ultravioletlight for the time of the one-line printing at the moment. That is, theirradiation time of the ultraviolet light to the last printed portion inthe UV black ink is shorter than that to the other printed portion, sothat the carriage 102 is moved at idle to irradiate the ultravioletlight to cover a shortfall. That is, the UV yellow ink is irradiatedwith ultraviolet light three times before the UV black ink is ejected,the UV magenta ink is irradiated twice before the UV black ink isejected, and the UV cyan ink is irradiated once before the UV black inkis ejected. Therefore, if the irradiation of the ultraviolet light isfinished when the ejection of the UV black ink in the last line iscompleted, the irradiation amount of the ultraviolet light to the areaof three lines from the last printed line is less than that to the otherportions. Due to lack of the irradiation, the viscosity of the UV blackink ejected in the last line may not be sufficiently increased or theink may not be sufficiently cured. To avoid this, the carriage 102 ismoved at idle the number of times that is one less than the number ofheads to average the time of the irradiation of the ultraviolet light.By doing so, the inks ejected onto the recording medium 103 are equallycured. After that, the CPU 201 extinguishes the UV lamps 105L, 105R(S310), and thus this processing has completed.

[0126] According to the color ink jet printer 100 of the firstembodiment, the UV lamps 105L, 105R are mounted on the carriage 102 tobe placed front and/or behind of the heads 104Y, 104M, 104C, 104K in themain scanning direction. Thus, cure of ink can be performed in parallelwith ink ejection from each heads 104Y, 104M, 104C, 104K. The color inkjet printer 100 does not become large in size, and the time required forprinting can be shortened. Further, the colors of the printing can beclearly represented.

[0127] The UV lamps 105L, 105R are longer than the heads 104Y, 104M,104C, 104K in the sub scanning direction, so that cure of ink can beperformed with respect to all heads 104Y, 104M, 104C, 104K at a time inparallel with ink ejection from the heads 104Y, 104M, 104C, 104K.Further, the substantially same amount of energy can be irradiated toeach color of ink on a recording medium 103, so that the ink can beevenly cured.

[0128] The active energy beam-curable composition of the presentinvention has been explained with reference to Examples. However, thepresent invention is not limited thereto. The active energy beam-curablecomposition can be constituted by using other components andcompositions within appended claims.3,4-Epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate has beenused as the photo-cationic polymerizable substance. In place of thiscompound, it is possible to use a variety of photo-cationicpolymerizable substances as described in the specification. Especially,it is preferable to use the oxetane compound as the photo-cationicpolymerizable substance. The active energy beam-curable composition ofthe present invention can be applied to a variety of objectives. Evenwhen the composition is heated after being cured, the occurrence of theodor and the cloudiness is suppressed.

What is claimed is:
 1. An active energy beam-curable compositioncomprising: a photo-cationic polymerizable substance; a photo-cationicpolymerization initiator; and a polymerizable compound having anethylenic unsaturated double bond.
 2. The composition according to claim1, wherein the polymerizable compound having the ethylenic unsaturateddouble bond is a monomer selected from the group consisting ofmonomethacrylate, dimethacrylate, monoacrylate, and diacrylate.
 3. Thecomposition according to claim 1, wherein the photo-cationicpolymerizable substance includes an epoxy resin compound.
 4. Thecomposition according to claim 3, wherein the epoxy resin compound is analicyclic epoxy resin compound.
 5. The composition according to claim 1,wherein the photo-cationic polymerizable substance is an oxetanecompound.
 6. The composition according to claim 1, wherein thephoto-cationic polymerization initiator contains an onium salt.
 7. Thecomposition according to claim 1, wherein the composition is an ink. 8.The composition according to claim 7, further comprising a coloringagent.
 9. An ink discharging apparatus comprising: an ink discharginghead which discharges an ink; an ink tank which stores the ink to besupplied to the ink discharging head; and a light source which is usedto cure the discharged ink, wherein the ink comprises: a photo-cationicpolymerizable substance; a photo-cationic polymerization initiator; anda polymerizable compound having an ethylenic unsaturated double bond.10. The ink discharging apparatus according to claim 9, wherein thepolymerizable compound having the ethylenic unsaturated double bond is amonomer selected from the group consisting of monomethacrylate,dimethacrylate, monoacrylate, and diacrylate.
 11. The ink dischargingapparatus according to claim 9, wherein the photo-cationic polymerizablesubstance includes an epoxy resin compound.
 12. The ink dischargingapparatus according to claim 11, wherein the epoxy resin compound is analicyclic epoxy resin compound.
 13. The ink discharging apparatusaccording to claim 9, wherein the photo-cationic polymerizable substanceis an oxetane compound.
 14. The ink discharging apparatus according toclaim 9, wherein the photo-cationic polymerization initiator contains anonium salt.
 15. The ink discharging apparatus according to claim 9,wherein the ink further comprises a coloring agent.